This version of Unity is unsupported.

ShaderKeyword.GetKeywordType

public static Rendering.ShaderKeywordType GetKeywordType(Shader shader, Rendering.ShaderKeyword index);
public static Rendering.ShaderKeywordType GetKeywordType(ComputeShader shader, Rendering.ShaderKeyword index);
Obsolete public Rendering.ShaderKeywordType GetKeywordType();

Description

Returns the type of keyword: built-in or user defined.